Bare die semiconductor devices can be incorporated into various products using roll-to-roll manufacturing method. For example, bare die light emitting diodes (LEDs) can be assembled into an LED sheet that can be used as a photo-radiation source for applications including, but not limited to, general illumination, architectural lighting, novelty lighting, display backlighting, heads-up displays, commercial and roadway signage, monochromatic and full-color static and video displays, a radiation-source for photo-curable materials, patterned light emissive images, and the like.
U.S. Pat. No. 7,259,030 to Daniels, et al. (which is incorporated herein by reference, in its entirety) discloses a roll-to-roll method of making a light active sheet that includes bare die LEDs disposed between planar electrodes. One embodiment of such a light active sheet is shown schematically herein in FIG. 1. The light active sheet 100 includes a bottom substrate 102 that has an electrically conductive upper surface (unnumbered). An insulative hot melt adhesive sheet 104 is provided, and a plurality of bare die LEDs 106 are embedded in the hot melt adhesive sheet. The hot melt adhesive sheet 104 with the bare die LEDs 106 embedded therein is disposed between the electrically conductive surface of the bottom substrate 102 and a transparent top substrate 120 to form a laminate. The top substrate 120 has a top planar electrode 122 that comprises a transparent conductive material (indium tin oxide (ITO)) mounted on a support layer 124. The support layer 124 comprises a transparent support material, i.e., polyethyleneterephthalate (PET). The laminate is run through a heated pressure roller system to melt the hot melt adhesive sheet 104 and electrically insulate and bind the top substrate 120 to the bottom substrate 102. As the hot melt sheet 104 softens, the bare die LEDs 106 break through and come into electrical contact with the top planar electrode 122 and the electrically conductive surface of the bottom substrate 102. The bottom substrate 102, the hot melt adhesive 104 (with the embedded bare die LEDs 106) and the top substrate 112 can be provided as rolls of material. The rolls are brought together in a continuous roll fabrication process, resulting in a flexible sheet of lighting material.